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CB750F3

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K2-K6:
I've always liked the F2 and it was the last of these motors produced. I know there's a general dislike of cleaning and looking after the PD carbs but they do work well when clean and setup I think.
It's the right way to run an engine too,  generally leaner when not accelerating helps to avoid unburnt excess fuel in both the oil and exhausts, it's just better for engine health.
I may be wrong but thought the valve guide wear was related to increased cam lift that moves the rockers through more of an arc which puts more sideways load onto the valve stem. If that's true, a K7 cam could possibly be used to avoid that long term.

Piki:
any pic from a F3? I have never seen a F3 before................ ??? ???

royhall:
They fitted bigger valves into the F2 so had to offset the rocker mechanism to get them in. The geometry change forces the valves into the outside of the guide causing wear so a K7 cam wouldn't help. They fixed the problem with harder valve guides. Failing that use the bronze guides from Kibblewhite.

yozzer74:
Royhall i sent mine to harpers too had know bother with them at all .

K2-K6:
Piki, the F3 I don't think you'd tell it apart from a F2 as they're essentially their same bike just moved the name along one notch,  did the same with the K7 to K8 as well. Think USA only.

Roy,  I know it's recorded some places ( I've found it mentioned in contemporary road tests)  that the F2 used different valve angle but I can't find anything official that says that,  don't know if anything exists.
I've seen the two head's apart but never next to each other to make a comparison directly. The F2 has bigger fins as far as I know but it just doesn't seem to me that the valve angle changed,  after all its only 3mm on exhaust and 2mm on inlet.  I'm not certain of it but certainly intrigued if they did change it.
Also,  more time ago than I want to remember,  a friend ran what I thought was K2 cam gear on an F2 head to replace a damaged set, or at least that's how I recall it.  I don't know how true that is but would obviously not be possible if the valve were moved.
They also seem to be in the same place inside the tappet adjust caps with the rocker covers being the same part it seems.
It don't know if anyone else on here has for example the rocker part numbers to compare perhaps.

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